Amide-containing diisocyanates and preparation thereof

ABSTRACT

Novel bis cyclic ureas are disclosed having the formula ##STR1## wherein C n  H 2  n represents alkylene from 4 to 12 inclusive and provided there are at least 4 carbon atoms in succession in the chain and R is the residue obtained by the removal of both halogen atoms from a diacid halide. 
     The bis cyclic ureas are easily converted to a novel class of aliphatic diisocyanates simply by heating. Alternatively, they are blended with polymeric polyols to form one-component storage stable compositions which are thermally converted to polyurethane resins without any significant volatile or side product formation.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of copending application Ser. No. 874,402filed Feb. 1, 1978, now U.S. Pat. No. 4,138,398, which in turn is acontinuation-in-part of copending application, Ser. No. 754,189, filedDec. 27, 1976 and now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the preparation of cyclic ureas, and, moreparticularly, is concerned with the preparation of bis cyclic ureaswhich can act as masked diisocyanates, the diisocyanates producedthereby, and the stable one-component polyurethane forming systemscontaining said bis cyclic ureas.

2. Description of the Prior Art

One-can, or the commonly named one-component, polyurethane formingsystems are well known, particularly, in the coating art; see forexample, Saunders & Frisch, Polyurethanes: Chemistry and Technology,Parts I (pp. 8 and 118-121) and II, (pp. 453-454), 1963 and 1964respectively, Interscience Publishers, John Wiley and Sons, New York, N.Y., and further references cited therein. The one-component systems callfor the use of a "blocked" or "disguised" isocyanate with a polyol. Uponheating the one-component system, the isocyanate groups are released toreact with the polyol to form the polyurethane. Unless, and until, thesystems are heated they remain shelf stable and avoid the need to storeand mix a number of separate components.

However, the blocked isocyanates suffer from the severe disadvantagethat when the blocking agent is released during the curing phase, it isliberated into the resin where it may remain and have a deleteriouseffect, or, alternatively, be vaporized off where it must either becollected or released to the atmosphere. Since the commonest blockingagent is phenol this gives rise to both safety and environmentalproblems, not to mention the economic ones.

We have now found a novel class of bis cyclic ureas which areparticularly useful in stable one-component polyurethane systems wherethey function as masked isocyanates. When the system is heated the bisureas dissociate to form only the diisocyanate thereby eliminating theprior art problem of a released blocking agent.

Furthermore, the compounds prepared from the bis cyclic ureas are,themselves, a novel class of amide containing diisocyanates which areuseful monomers in applications other than one-component polyurethanesystems and are very simply prepared from said ureas.

SUMMARY OF THE INVENTION

This invention comprises bis cyclic ureas having the formula ##STR2##wherein C_(n) H_(2n) represents alkylene from 4 to 12, inclusive,provided there are at least 4 carbon atoms in succession in the chainand R is a divalent radical selected from the group consisting of##STR3## wherein C_(x) H_(2x) represents alkylene from 1 to 8 inclusive,and ##STR4##

The invention also comprises a process for the preparation of the novelbis cyclic ureas (I).

The invention also comprises a process for converting a bis cyclic urea(I) into a diisocyanate having the formula

    OCN--C.sub.n H.sub.2n --NH--R--NH--C.sub.n H.sub.2n --NCO  (II)

wherein C_(n) H_(2n) and R are as defined above.

The invention also comprises the diisocyanates having the formula (II)set forth above.

The invention also comprises a storage stable composition, capable offorming a polyurethane resin upon heating said composition to atemperature in the range of about 100° C. to about 250° C., saidcomposition comprising a mixture of a bis cyclic urea (I) and apolymeric polyol.

The invention also comprises a polyurethane resin prepared by reacting abis cyclic urea (I) with a polymeric polyol.

The diradical --C_(n) H_(2n) -- means an alkylene radical having from 4to 12 carbon atoms, inclusive, such as butylene (tetramethylene),pentylene (pentamethylene), hexylene (hexamethylene), heptylene(heptamethylene), octylene (octamethylene), nonylene (nonamethylene),decylene (decamethylene), undecylene (undecamethylene), dodecylene(dodecamethylene), and isomeric forms thereof provided there are atleast 4 carbon atoms in succession in the chain separating the valencies

The diradical --C_(x) H_(2x) -- means an alkylene radical having from 1to 8 carbon atoms, inclusive, such as methylene, ethylene, propylene,butylene, pentylene, hexylene, heptylene, octylene, and isomeric formsthereof.

The term "storage stable composition" means a composition capable ofstanding for an indefinite period of time at a temperature of about 20°C.-30° C. without undergoing a chemical change.

The term "polymeric polyol" means any organic polyol having an averagehydroxyl equivalent weight of from about 30 to about 1,500 and havingfrom about 2 to about 8 hydroxyl groups per molecule.

The term "polymeric diol" means a polymeric polyol defined above andhaving 2 hydroxyl groups.

The term "difunctional extender" means a difunctional active hydrogencontaining compound inclusive of glycols, diamines, amino-alcohols, andthe like.

DETAILED DESCRIPTION OF THE INVENTION

The novel bis cyclic ureas of the present invention having the formula(I) set forth above are easily prepared in a novel process using theSchotten-Baumann reaction conditions for the acylation of amines orureas; for example, see Synthetic Organic Chemistry by R. B. Wagner andH. D. Zook, p. 647, 1953, John Wiley and Sons, New York, N. Y.Typically, the appropriate cyclic urea (III) and diacid halide (IV) arereacted in an inert organic solvent at a molar ratio of 2:1 respectivelyand in the presence of a 2 molar proportion of an acid acceptor basecompound to remove the 2 moles of HX formed from the reaction inaccordance with the following equation ##STR5## wherein the diradicals--C_(n) H_(2n) -- and --R-- are as defined above and X is a halogenselected from the group consisting of fluorine, chlorine, bromine, andiodine.

A preferred class of novel bis cyclic ureas (I a) in accordance with thepresent invention is that prepared from the cyclic urea (III a) and adiacid halide (IV a) in accordance with the following equation ##STR6##wherein n is an integer from 4 to 6 inclusive.

The preparative conditions involve procedures well known to thoseskilled in the art and are not critical to the present invention andoptimum conditions can be easily determined by trial and error. Thereaction temperature can range from about 20° C. to about 100° C. andpreferably is from about 20° C. to about 80° C. The reaction time isadvantageously from about 10 minutes to about 8 hours.

Typical solvents for the reaction include ethylene dichloride,chlorobenzene, ortho-dichlorobenzene, methylethyl ketone, acetonitrile,diethyleneglycol dimethyl ether, ethyleneglycol dimethyl ether, and thelike.

Any base capable of removing hydrohalic acids from the reaction may beused and includes either an inorganic or organic base although thelatter is generally preferred. Typical inorganic bases which can beemployed are sodium hydroxide, potassium hydroxide, calcium oxide, andthe like. Typical organic bases include tertiary amines such aspyridine, triethylamine, tributylamine, and the like. Generallyspeaking, when the tertiary amines are employed they form insolubleamine hydrohalide salts which are easily removed by filtration whereasan inorganic base such as sodium hydroxide results in the formation ofthe sodium halide salt and water which are both easily separated fromthe bis cyclic urea using liquid extraction procedures well known tothose skilled in the art.

The bis cyclic ureas are readily obtained from the reaction mixtureusing standard product isolation techniques known to those skilled inthe art. Generally speaking, after the hydrohalide salt is removed fromthe reaction mixture by filtration, the solution is concentrated byremoving the solvent, preferably in vacuo, and the residue is trituratedor recrystallized from water or other suitable solvent to yieldcrystalline (I).

The cyclic ureas (III) employed in the preparation of the bis cyclicureas in accordance with the present invention are known compounds whichare readily obtained using standard methods known in the art.

A preferred cyclic urea employed in the present invention has theformula (III a) set forth above.

Illustratively, the cyclic ureas (III) are easily obtained by the methodof Ozaki et al, (J.A.C.S. 79, 4358-4360, 1957) starting with theappropriate diisocyanate (V) which is converted to the cyclic urea (III)by reaction with water.

    OCN--C.sub.n H.sub.2n --NCO+H.sub.2 O→III+CO.sub.2  V

Illustrative examples of the cyclic ureas (III) used in the presentinvention include tetramethylene urea, pentamethylene urea,hexamethylene urea, heptamethylene urea, octamethylene urea,nonamethylene urea, decamethylene urea, undecamethylene urea,dodecamethylene urea, 5,5-dimethyltetramethylene urea,5,6-dimethyltetramethylene urea, 5,5-dimethyl heptamethylene urea, andthe like.

A preferred group of cyclic urea includes tetramethylene urea,pentamethylene urea, and hexamethylene urea.

The diacid halides (IV) employed in the practice of the presentinvention are defined as above and a preferred diacid halide has theformula ##STR7## wherein X is defined hereinabove.

Exemplary of the diacid halides that can be used in the presentinvention are succinoyl dichloride, glutaroyl dichloride, adipoyldichloride, pimeloyl dichloride, suberoyl dichloride, azelaoyldichloride, sebacoyl dichloride, adipoyl dibromide, azelaoyl dibromide,sebacoyl dibromide, terephthaloyl dichloride, isophthaloyl dichloride,and phthaloyl dichloride.

A preferred group of diacid halides comprises adipoyl dichloride,azelaoyl dichloride, sebacoyl dichloride, terephthaloyl dichloride,isophthaloyl dichloride, and phthaloyl dichloride.

A particularly preferred group consists of terephthaloyl dichloride,isophthaloyl dichloride, and phthaloyl dichloride.

Although the bis cyclic ureas (I) in accordance with the presentinvention find particular utility as masked diisocyanates inone-component polyurethane systems which will be discussed in detailhereinafter, they also serve as a convenient source for a class of noveldiisocyanates having the formula (II) set forth above.

The diisocyanate (II) is obtained simply by heating the bis cyclic ureaat a temperture high enough to cause its dissociation. The heating maybe carried out in the absence of solvent, however, the bis cyclic ureas(I) in their most purified form are crystalline compounds and it isgenerally preferable to carry out the conversion in a solvent in theabsence of moisture. The resulting solution of the diisocyanate (II) canthen be employed in some further operation in the form of a solution,or, optionally, the solvent may be removed using standard methods knownto those skilled in the art, for example, distillation, vacuumconcentration, thin-film evaporation, etc., to provide the purediisocyanate.

The conversion is advantageously carried out within a temperature rangeof about 100° C. to about 250° C., preferably from about 150° C. toabout 180° C. for a period of time from about 5 minutes to about 5 hoursand preferably from about 10 minutes to about 30 minutes.

Solvent choice is not critical and any solvent which is inert to boththe bis urea (I) and diisocyanate (II) may be used in the dissociationreaction provided its boiling point is high enough to permit heating ofthe solution to affect the dissociation of I to II. Typical solventsinclude those used in the preparation of the bis cyclic ureas (I) setforth above. Advantageously, the same solvent in which the urea (I) isprepared is used for the dissociation reaction.

A preferred class of diisocyanates are those having the formula ##STR8##

These diisocyanates are obtained from the dissociation of the bis cyclicureas having the formula (I a) set forth above.

The diisocyanates (II) embrace a novel class which includes (a)aliphatic amide containing aliphatic diisocyanates, and (b) aromaticamide containing aliphatic diisocyanates. These diisocyanates can beconverted to a variety of condensation polymers using procedures wellknown in the art. Illustratively, they can be converted to non-cellularpolyurethanes for use in elastomers, coatings, fibers, and adhesives,using procedures such as those described in Saunders et al,Polyurethanes, Chemistry and Technology, Part II, IntersciencePublishers, New York, 1964. The polyurethanes so prepared arecharacterized by greater color stability on exposure to sunlight orultraviolet irradiation compared with corresponding polyurethanesprepared from aromatic diisocyanates.

The bis cyclic ureas (I) find particular utility as masked diisocyanatesin one-component or one-can polyurethane systems. The bis cyclic urea(I) is thoroughly blended with a polymeric polyol in essentiallystoichiometric proportions at a temperature below 65° C., preferablyfrom about 20° C. to about 65° C., using any suitable mixing procedureknown to those skilled in the art, and preferably under anhydrousconditions to exclude moisture.

The resulting blend is a storage stable composition which can be storedfor an indefinite period of time at a reasonable ambient temperature,for example 20°-30° C., without undergoing reaction to formpolyurethane.

Upon heating said storage stable composition to a temperature in therange of about 100° C. to about 250° C., the bis cyclic urea (I) andpolymeric polyol undergo reaction to form a polyurethane resin. Heatingtime should be sufficient to complete the reaction between the polyoland masked isocyanate and will vary according to the viscosity of theblend composition, the chemical structure of the polyol, and thepresence or absence of a polyurethane catalyst, and, most importantly,temperature. Optimum conditions of time and temperature for any givensystem are easily determined by trial and error on small aliquot samplesof the composition.

It is frequently desirable, but not essential, to include a catalyst inthe reaction mixture employed to prepare the compositions of theinvention. Any of the catalysts conventionally employed in the art tocatalyze the reaction of an isocyanate with a reactive hydrogencontaining compound can be employed for this purpose; see for example,Saunders et al., Polyurethanes, Chemistry and Technology, Part I,Interscience, New York, 1963, pages 228-232; see also Britain et al., J.Applied Polymer Science, 4, 207-211, 1960. Such catalysts includeorganic and inorganic acid salts of, and organometallic derivatives of,bismuth, lead, tin, iron, antimony, uranium, cadmium, cobalt, thorium,aluminum, mercury, zinc, nickel, cerium, molybdenum, vanadium, copper,manganese and zirconium, as well as phosphines and tertiary organicamines. Representative organotin catalysts are stannous octoate,stannous oleate, dibutyltin dioctoate, dibutyltin dilaurate, and thelike. Representative tertiary organic amine catalysts are triethylamine,triethylenediamine, N,N,N',N'-tetramethylethylenediamine,N,N,N',N'-tetraethylethylenediamine, N,methylmorpholine,N-ethylmorpholine, N,N,N',N'-tetramethylguanidine,N,N,N',N'-tetramethyl-1,3-butanediamine, N,N-dimethylethanolamine,N,N-diethylethanolamine, and the like. The amount of catalyst employedis generally within the range of about 0.02 to about 2.0 percent byweight based on the total weight of the reactants.

The polymeric polyols employed in the storage stable composition anddefined hereinabove include any of the polyols set forth in U.S. Pat.Nos. 3,745,133 and 3,423,344 the disclosures of which are incorporatedherein by reference.

It will be understood by those skilled in the art that when thepolymeric polyol employed in the storage stable compositions of theinvention has more than two hydroxy groups, the resulting polyurethaneresin will be highly cross-linked and give rise to a solid, hard, andhigh modulus polyurethane resin in the absence of modifying agents.Polyurethanes produced thereby can be used particularly for potting andencapsulating electrical components.

In a preferred embodiment of the storage stable compositions inaccordance with the present invention the bis cyclic ureas (I a) areblended with a mixture of a polymeric diol as defined above, and adifunctional extender, and a polyurethane catalyst. Upon heating, thiscomposition is converted to an elastomeric polyurethane resin. Theproportions of urea and diol extender combination are chosen so that theratio of the equivalents of isocyanate arising from the ureadissociation to the total number of hydroxyl or active hydrogen groupsin the polymeric diol and extender is within the range of 0.95:1 to1.10:1 and preferably within the range of 0.98:1 to 1.04:1. Further, aswill be appreciated by one skilled in the art, the proportion ofpolymeric diol to extender can be varied within a wide range dependinglargely upon the desired hardness of the final polyurethane elastomer.Advantageously, the molar proportion of polymeric diol to extender iswithin the range of 0.05:1 to 2:1 and, preferably, within the range of0.1:1 to 1:1.

If desired, the elastomers of the invention can have incorporated inthem, at any appropriate stage of preparation, additives such aspigments, fillers, lubricants, stabilizers, antioxidants, coloringagents, fire retardants, and the like, which are commonly used inconjunction with polyurethane elastomers.

Exemplary of the polymeric diols which can be employed in the storagestable compositions of the invention are hydroxyl terminated polyestersor polyethers. Illustrative of the polyether polyols are polyoxyalkyleneglycols such as polytetramethylene glycol, the polyoxyethylene glycolsprepared by the addition of ethylene oxide to water, ethylene glycol ordiethylene glycol; polyoxypropylene glycols prepared ty the addition of1,2-propylene oxide to water, propylene glycol or dipropylene glycol;mixed oxyethylene oxypropylene glycols prepared in a similar mannerutilizing a mixture of ethylene oxide or propylene oxide or a sequentialaddition of ethylene oxide and 1,2-propylene oxide; polyether glycolsprepared by reacting ethylene oxide, propylene oxide, or mixturesthereof with mono- and polynuclear dihydroxybenzene, e.g. catechol,resorcinol, hydroquinone, orcinol, 2,2-bis(p-hydroxyphenyl)propane,bis(p-hydroxyphenyl)methane and the like.

Illustrative of polyester polyols are those prepared by polymerizingε-caprolactone using an initiator such as ethylene glycol, ethanolamineand the like, and those prepared by esterification of polycarboxylicacids such as phthalic, terephthalic, succinic, glutaric, adipic acidsand the like with polyhydric alcohols such as ethylene glycol,butanediol, and the like.

The difunctional extenders which can be employed in preparing thestorage stable compositions of the invention can be any of thedifunctional active hydrogen containing extenders commonly employed inthe art. The latter are inclusive of glycols, diamines, amino alcohols,and the like. Illustrative of diol extenders are aliphatic diols,advantageously containing from 2 to 6 carbon atoms, inclusive, such asethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol,1,4-butanediol, 1,2-hexanediol, neopentyl glycol, and the like; anddihydroxyalkylated aromatic compounds such as thebis(2-hydroxyethyl)ethers of hydroquinone and resorcinol;p-xylene-α,α'-diol; the bis(2-hydroxyethyl)ether of p-xylene-α,α'-diol;m-xylene-α,α'-diol and the bis(2-hydroxyethyl)ether thereof.Illustrative of diamine extenders are aromatic diamines such asp-phenylenediamine, m-phenylenediamine, benzidine,4,4'-methylenedianiline, 4,4'-methylenebis(2-chloroaniline) and thelike. Illustrative of amino alcohols are ethanolamine, propanolamine,butanolamine, and the like.

The storage stable compositions can be used in the preparation of (i)polyurethane coatings, particularly wire coating; (ii) coatings formetals because of their high adhesion properties to metals and othersurfaces due to free isocyanate generation upon heating; and (iii)sealants, gaskets, seals, and the like. Furthermore, these applicationsof the compositions of the invention can be conducted at elevatedtemperatures and do not give rise to any volatile by-product formation.

The following examples describe the manner and process of making andusing the invention and set forth the best mode contemplated by theinventors of carrying out the invention but are not to be construed aslimiting.

EXAMPLE 1

A 250 ml. reaction flask equipped with a mechanical stirrer, a refluxcondenser, thermometer, and addition funnel was charged with 6.84 g.(0.06 mole) of tetramethylene urea, 10.1 g. (0.1 mole) of triethylamine,and 150 ml. of ethylene dichloride. The mixture was stirred to form asolution and, at room temperature (about 25° C.) and over a period ofabout 22 minutes, a solution of 6.09 g. (0.03 mole) of isophthaloylchloride, dissolved in 30 ml. of ethylene dichloride, was added duringconstant stirring. Reaction temperature during the addition slowly roseto 42° C. and the solution became cloudy as a precipitate formed.

The reaction mixture was cooled and filtered to collect 5.95 g. of thehydrochloride salt of triethylamine. Evaporation of the filtrateprovided 20.05 g. of thick liquid residue. It was triturated in excessethyl acetate until it was crystalline then filtered. A crystallinesolid was obtained, wt.=6.75 g., m.p.=185°-200° C. The crystalline solidwas triturated in 100 ml. of water, filtered, washed with fresh water,and dried to yield 3 g. of crystalline N,N'-isophthaloylbis(tetramethylene urea) which melted at 225°-230° C. This compound is abis cyclic urea in accordance with the present invention and correspondsto the following formula ##STR9##

Using the procedure and ingredients set forth above except that eitherthe isophthaloyl chloride is replaced by the equivalent amount of thefollowing diacid chlorides, or else the tetramethylene urea is replacedby the equivalent amount of the following cyclic ureas, there areproduced the corresponding bistetramethylene ureas and N,N'-isophthaloylbis cyclic ureas in accordance with the present invention.

    ______________________________________                                        Diacid chloride Bistetramethylene urea                                        ______________________________________                                        Terephthaloyl chloride                                                                        N,N'-Terephthaloyl bis(tetra-                                                 methylene urea)                                               Adipoyl chloride                                                                              N,N '-Adipoyl bis(tetramethylene                                              urea)                                                         Azelaoyl chloride                                                                             N,N'-Azelaoyl bis(tetramethylene                                              urea)                                                         Sebacoyl chloride                                                                             N,N'-Sebacoyl bis(tetramethylene                                              urea)                                                         α-Methyladipoyl chloride                                                                N,N'-(α-Methyladipoyl)bis                                               (tetramethylene urea)                                         ______________________________________                                        Cyclic Urea     Bis Cyclic Urea                                               ______________________________________                                        Pentamethylene urea                                                                           N,N'-Isophthaloyl bis(penta-                                                  methylene urea)                                               Hexamethylene urea                                                                            N,N'-Isophthaloyl bis(hexa-                                                   methylene urea)                                               Octamethylene urea                                                                            N,N'-Isophthaloyl bis(octa-                                                   methylene urea)                                               5,5-Dimethyltetra-                                                                            N,N'-Isophthaloyl bis(5,5-                                    methylene urea  dimethyltetramethylene urea)                                  5,6-Dimethyltetra-                                                                            N,N'-Isophthaloyl bis(5,6-                                    methylene urea  dimethyltetramethylene urea)                                  ______________________________________                                    

Stability of N,N'-Isophthaloyl Bis(Tetramethylene Urea)

A 0.5 g. sample of N,N'-isophthaloyl bis(tetramethylene urea) and 25 ml.of methanol were heated for 5 hours under reflux (temperature range of64° C.-67° C.). The mixture was cooled then filtered to obtain 0.3 g. ofthe starting compound, m.p.=235°-240° C. The remainder of the startingbis urea was soluble in the methanol. The N,N'-isophthaloylbis(tetramethylene urea) was therefore characterized as stable at 65° C.since no carbamate formed upon heating in the methanol.

Dissociation of N,N'-Isophthaloyl Bis(Tetramethylene Urea) toN,N'-Di(4-Isocyanatobutyl)Isophthalamide

A 0.25 g. sample of N,N'-isophthaloyl bis(tetramethylene urea) and 10ml. of ortho dichlorobenzene (ODCB) were placed in a 25 ml. round bottomflask equipped with a reflux condenser, stirrer and thermometer. Themixture was heated during stirring and when the solution started toreflux (at 180° C.), samples of the solution were removed and analyzedby infrared absorption spectroscopy. Isocyanate absorption at 4.34μ wasevident in the first sample taken and dissociation of the diurea wascomplete within 30 minutes at 180° C. Thus there was obtainedN,N'-di(4-isocyanatobutyl)isophthalamide in accordance with the presentinvention and corresponding to the formula ##STR10##

It was characterized by infrared absorption analysis including thecharacteristic isocyanate absorption at 4.34μ.

Using the above procedure of heating in ODCB at 180° C. thebistetramethylene ureas and bis cyclic ureas set forth below there areproduced the corresponding diisocyanates in accordance with the presentinvention set forth below.

    ______________________________________                                        Bis Urea          Diisocyanate                                                ______________________________________                                        N,N'-Terephthaloyl bis                                                                          N,N'-Di(4-isocyanatobutyl)                                  (tetramethylene urea)                                                                           terephthalamide                                             N,N'-Adipoyl bis(tetra-                                                                         N,N' -Di(4-isocyanatobutyl)                                 methylene urea)   adipamide                                                   N,N'-Azelaoyl bis(tetra-                                                                        N,N'-Di(4-isocyanatobutyl)                                  methylene urea)   azelamide                                                   N,N'-Sebacoyl bis(tetra-                                                                        N,N'-Di(4-isocyanatobutyl)                                  methylene urea)   sebacamide                                                  N,N'-(α-Methyladipoyl)bis                                                                 N,N'-Di(4-isocyanatobutyl)                                  (tetramethylene urea)                                                                           α-methyladipamide                                     N,N'-Isophthaloyl bis(penta-                                                                    N,N'-Di(5-isocyanatopentyl)                                 methylene urea)   isopthalamide                                               N,N'-Isophthaloyl bis(hexa-                                                                     N,N'-Di(6-isocyanatohexyl)                                  methylene urea)   isophthalamide                                              N,N'-Isophthaloyl bis(octa-                                                                     N,N'-Di(8-isocyanatooctyl)                                  methylene urea)   isophthalamide                                              N,N'-Isophthaloyl bis(5,5-                                                                      N,N'-Di(4-isocyanato-2,2-                                   dimethyltetramethylene                                                                          dimethylbutyl)isophthal-                                    urea)             amide                                                       N,N'-Isophthaloyl bis(5,6-                                                                      N,N'-Di(4-isocyanato-2,3-                                   dimethyltetramethylene                                                                          dimethylbutyl)isophthal-                                    urea)             amide                                                       ______________________________________                                    

EXAMPLE 2

A 1.79 g. (0.005 mole) sample of N,N'-isophthaloyl bis(tetramethyleneurea) and 3.31 g. (0.005 mole) of Teracol 650 (a tetramethyleneglycol,E.W.=331, supplied by E. I. DuPont Company, Wilmington, Del.) were mixedin a test tube and degassed at 100° C. under vacuum of about 0.1 mm. Thereactants were not completely miscible at this temperature.

The temperature was slowly raised and at 210°-215° C. a clearhomogeneous solution had formed. Heating was continued at about220°-230° C. for 15 minutes then the hot clear solution was poured intoan aluminum dish. Upon cooling, it formed a hard resilient dark yellowpolymer characterized by the following recurring unit ##STR11## whereinR corresponds to the divalent residue formed by the removal of the twohydroxyl groups of Teracol 650.

We claim:
 1. A process for converting a bis cyclic urea having theformula ##STR12## into a diisocyanate having the formula

    OCN--C.sub.n H.sub.2n --NH--R--NH--C.sub.n H.sub.2n --NCO

wherein C_(n) H_(2n) is the same in each formula and is alkylene from 4to 12 inclusive and provided there are at least 4 carbon atoms insuccession in the chain and R is the same in each formula and is adivalent radical selected from the group consisting of ##STR13## whereinC_(x) H_(2x) is alkylene from 1 to 8 inclusive, and ##STR14## whichprocess comprises heating said bis cyclic urea at a temperaturesufficiently high to open both rings of said cyclic urea to form saiddiisocyanate.
 2. A process according to claim 1 wherein n is an integerfrom 4 to 6 inclusive and R is a divalent radical having the formula##STR15##
 3. A process according to claim 2 wherein n=4 and R is adivalent radical having the formula ##STR16##
 4. A diisocyanate havingthe formula

    OCN--C.sub.n H.sub.2n --NH--R--NH--C.sub.n H.sub.2n --NCO

wherein C_(n) H_(2n) is alkylene from 4 to 12 inclusive and providedthere are at least 4 carbon atoms in succession in the chain and R is adivalent radical selected from the group consisting of ##STR17## whereinC_(x) H_(2x) is alkylene from 1 to 8 inclusive, and ##STR18##
 5. Adiisocyanate according to claim 4 wherein R is a divalent radical havingthe formula ##STR19## wherein C_(x) H_(2x) is alkylene from 1 to 8inclusive
 6. A diisocyanate according to claim 4 wherein R is a divalentradical having the formula ##STR20##
 7. A diisocyanate having theformula ##STR21## wherein n is an integer from 4 to 6 inclusive.
 8. Adiisocyanate according to claim 7 having the formula ##STR22##